"I'm afraid that carriers desperate for one-upmanship will make 4G a meaningless technical term," Gartner analyst Ken Dulaney said in an e-mail interview. "All it's going to mean is that it's faster than the last network you were on."

The only technologies that will qualify as 4G are a future version of LTE (Long-Term Evolution), to be called LTE-Advanced, and the next generation of WiMax, officially known as IEEE 802.16m or WirelessMAN-Advanced, according to the ITU's Radiocommunication Sector.

Neither of these is expected to go live commercially until 2014 or 2015, because the ITU said its target for 4G is a speed of 100M bps (bits per second) downstream with high mobility and 1G bps with limited mobility. So LTE and WiMax, which have been advertised as 4G for years, have no official claim on the title either.

The war of words over 4G is nothing new. Before there was a technical definition from the ITU or ubiquitous advertising by carriers, there were spectrum licensing requirements by national governments. Certain blocks of frequencies auctioned off or assigned in recent years have come with a requirement that they be used for next-generation mobile networks instead of 3G, said Tolaga Research analyst Phil Marshall. This was one reason the backers of WiMax fought so hard to make sure their technology was defined as something new.

The battle over the use of 4G seems to be most heated in the U.S., said Marshall, who is based in Boston. Most carriers in Western Europe are following the same well-defined path from HSPA to LTE, while in Asia, WiMax and LTE have sharply staked out the 4G territory. In many developing countries, these two technologies are being deployed first for residential broadband, he said.

Both WiMax and LTE truly are a new type of network, and are similar one to the other. Both are IP (Internet Protocol) networks from end to end, and both use a technology called OFDMA (Orthogonal Frequency-Division Multiplexing Access). In addition, each has a migration path to one of the super-fast future networks that will be officially 4G, Marshall said.

T-Mobile said it works with the ITU on its future standards but points out that those official 4G technologies aren't in the real world yet. "It's all conjecture," said Mark McDiarmid, senior director of engineering at T-Mobile. "For us, 4G is really about the consumer experience."

"What we're selling today ... is clearly the equivalent or the better of what's being marketed today as 4G," McDiarmid said. The HSPA+ network delivers on average 5M bps downstream to smartphones and 12M bps to laptop dongles, McDiarmid said. By way of comparison, Clearwire quotes average speeds of 3M bps to 6M bps for its WiMax network, which is also sold by Sprint Nextel, and Verizon Wireless says its LTE network set for launch later this year has shown speeds of 5M bps to 12M bps.

It makes sense for T-Mobile to pick up the much-used term, said analyst Peter Jarich of Current Analysis.

"If I'm in a market where everyone else is calling their stuff 4G, and I think that my services (are) going to be comparable, then I kind of owe it to my shareholders ... to call myself 4G," Jarich said.

These broad uses of the term "4G" aren't likely to hurt consumers, analysts said. Networks and devices either deliver the promised experience or don't, and the subscriber will have to upgrade before taking advantage of any network migration path anyway, they said.

"What we're talking about is one piece of the puzzle," said Yankee Group analyst Chris Nicoll. "It's actually the device that has a huge impact on users' perception of their network and of their user experience." In a Yankee survey, AT&T users with Apple iPhones rated the carrier's 3G network more highly than those with less advanced feature phones, he said.

because the industry has essentially defined 4G for itself, throwing the terminology around may not even be confusing for consumers, Tolaga's Marshall said.

"Given that we've already created an expectation of a certain level of performance as qualifying for 4G, then perhaps it isn't," Marshall said.

However, today's 4G claims could come back to haunt mobile operators down the road, he said. The industry is doing the same thing with 4G that it did with 3G in the early part of the last decade. Early mobile data technologies such as CDMA2000-1x and EDGE (Enhanced Data Rates for GSM Evolution) were labeled 3G, only to get demoted a few years later when the true 3G systems EV-DO (Evolution-Data Optimized) and UMTS (Universal Mobile Telecommunications System) were deployed, he said. The earlier networks are now typically called 2.5G or 2.75G.

So when it comes time to roll out LTE-Advanced and WirelessMAN-Advanced, what's proudly called 4G today may get a new name.